1. Field of the Invention
This invention relates to a sanding rasp, and is more particularly concerned with a hand-held sanding rasp designed to permit the user to readily change the sanding element. The rasp includes a heavy grit sandpaper immovably attached to a substrate which is adapted to be releasably secured to the rasp's support plate.
2. Description of the Prior Art
Recently, the utilization of coated, expanded polystyrene in exterior wall construction has become widely used. The process of assemblying such an exterior wall includes mounting sheets of expanded polystyrene (EPS), typically sized in 4'.times.8' sheets, to a support grid. The EPS sheets are placed along the support grid, with each of their respective edges abutting, so that the exterior wall includes a system of EPS panels arranged with no spaces or cracks between the abutting edges. Aligning each abutting edge, therefore, is a joint. After the joints of the EPS panels are prepared, as is discussed hereinafter, the system of EPS panels are then sprayed with a polymer modified cementitious coating having an acrylic polymer finish. As this coating cures, it is worked to the desired finish and allowed to set. Exterior wall systems of this type are becoming increasingly popular because of their low expense of erection, durability, and appearance.
A critical preparatory step in achieving a desirable final product in terms of appearance and durability, is the proper preparation of the joints between each EPS panel prior to applying the polymer coating. Practically, when the EPS panels are attached to the support grid, the joints between the panels are uneven, or are not flush. In other words, there is often a ridge along the joint line where the respective panels abut, because of variations in the support grid or the attachment of the EPS Panels to the support grid. This necessitates that the joints be properly prepared prior to the application of the polymer coating, so that the joints are smooth. In preparing the joints, the abutting panels are "blended" by sanding the area of the abutting panels around the joints, so that the panels slope gradually toward the joint, avoiding any abrupt indentations. If the joints are not carefully prepared in this manner, the final finish after the coating is applied may be greatly inundated, thus adversely affecting appearance and durability.
The preparation of the joints is a labor intensive process, because this preparation must be carefully performed. The preparation of the joints is rendered even more labor intensive, however, because of the inadequacies of the tools presently used by the industry to prepare the joints. Because of the physical properties of expanded polystyrene, the medium used to sand the EPS must be very coarse. Typically, a coarse sandpaper, such as 12 to 16 grit paper is used. Additionally, the physical properties of the EPS panels require that the sandpaper be immovably mounted to a sanding apparatus when the EPS panels are sanded. This is because if the sandpaper moves on the sanding apparatus, even to a small extent, a large indentation may be unintentionally cut into the EPS panels, requiring that the panel be replaced and the respective joint be prepared a second time. Because of this fact, those in the trade are presently cementing, by permanent epoxy, the heavy grit sandpaper to the bottom of boards, or sometimes to an aluminum apparatus resembling a cement float. The sandpaper is glued to the bottom of the sanding apparatus, because those in the construction industry realize that the paper cannot be wrapped around the apparatus and secured along the top, as has been previously done in common sanding rasps. This is because this method of securing the paper to the rasp inevitably permits the sandpaper to move or shift on the rasp, either immediately or after it is applied to the rasp or soon thereafter as the integrity of the sandpaper deteriorates by use. Therefore, the industry is solving this problem currently, by gluing the sandpaper to the sanding apparatus to ensure that the paper does not slip or move.
The use of this presently used apparatus, however, has numerous inherent disadvantages. The first is that because the sandpaper is securely cemented or epoxied to the sanding apparatus, the sandpaper cannot be readily removed when the paper is worn to a nonusable extent. Presently, the industry is soaking the sanding apparatus in strong chemical solutions in order to soften the epoxy Then the chemically treated sandpaper is scraped off of the sanding apparatus. The apparatus is then allowed to dry, and a new sheet of sandpaper is immovably cemented or epoxied thereon. This procedure is time consuming, messy, and inefficient. Also, those preparing the joints using this present apparatus, are continuing to use sandpaper past the point when the paper retains an accePtable amount of abrasive medium, because the user does not want to stop the preparation and proceed with the time consuming process of removing the epoxied sandpaper from the sanding apparatus. This is further causing problems in joint preparation.
The present invention overcomes the problems encountered by the prior-used methods, and allows the sandpaper to be not only immovably fixed to the sanding rasp, but also to be readily removed and replaced, as needed, quickly and efficiently.